1. The Field of the Invention
The present invention is directed generally to an apparatus for canceling resonance created in a burner. More specifically, the present invention is directed to an apparatus for canceling resonance in burner created when the burner demand changes rapidly from a medium or high demand to a low demand or when the burner demand is set at an even lower level.
2. Background Art
When a burner demand is altered rapidly from a medium or high demand to a low demand, e.g., in a burner with high turndown, the now lowered fuel/air mixture flowrate can cause a resonance in the burner hardware, e.g., the burner tube, which is audible. Further, this also causes poor combustion at the burner, resulting in high carbon monoxide (CO) and nitrogen oxide (NOX) contents in the exhaust of the burner.
U.S. Pat. No. 6,428,312 to Smelcer et al. (hereinafter Smelcer) discloses a burner apparatus including a foraminous burner surface having a multitude of openings through which flames can extend. The burner surface is irregularly shaped so that flames extending from the openings are directed in an irregular pattern whereby eddy currents are generated and effectively disrupt oscillation of the flames to result in reduced noise generation from flame oscillation. Smelcer's means for eliminating burner resonance involves making the surface of a burner irregular. Such practice requires significant changes to conventional burners to result in the irregularly shaped burner surfaces. It may be impractical to modify an existing burner to result in Smelcer's burner. In addition, the modification involves adding or using a component which comes in direct contact with flames during combustion and therefore the burner surface material must be made from a substance which can withstand such use. Further, if Smelcer's concept were to be applied to an existing burner to result in a rigid burner having an irregular surface, the amount of modification and/or level of effort required are even greater.
Thus, there is a need for a burner capable of mitigating the effects of burner resonance or an apparatus capable of being adapted to a burner to mitigate the effects of burner resonance and in at least one version, doing it without requiring a complete change-out of existing burners or significant additions to the existing burners.